1. Field of the Invention
The present invention relates to a polymerizable monomer useful as a starting material for producing high hardness transparent resins. The high hardness transparent resins can be used to prepare laminated transparent plastic material. The laminated transparent plastic material may be used as a transparent material for a glazing material such as outside windows of vehicles, rail way trains, airplanes or the like required to have good visibility, protecting function and safety, windows of the partition plates in the vehicles, airplanes or the like, outside windows of various buildings and edifices, and parts of roofs, ceilings and walls through which light is introduced thereinto, or as a protective cover for measuring instruments or various machines and apparatuses.
2. Description of Related Art
Inorganic glass is excellent not only in transparency, but also in various other physicals properties, and therefore, it is widely used as a transparent material.
However, inorganic glass is easily broken and the shape of the broken piece is dangerous so that it has been problematic from the standpoint of safety. Moreover, various lightweight materials have been recently demanded, and therefore there is a strong tendency that inorganic glass as a transparent material is replaced by transparent resins and composite resin.
Heretofore, transparent thermoplastic resin shaped articles, in particular, those of polymethyl methacrylate resin, polycarbonate resins and the like, have been used for various purposes since these molded articles are excellent in transparency, mechanical properties, in particular, impact resistance, further, workability and productivity, and have also good appearance. Examples of applications of transparent thermoplastic resin molded articles include glazing materials, for example, windows for buildings such as educational or cultural facilities, sports facilities, railway station buildings and the like, a part of roofs, protecting walls such as shelter for superhighway and the like, and water tanks for aquariums.
In addition, transparent thermoplastic resin shaped articles are used as protective covers for liquid crystal apparatuses and lighting apparatuses, and display appratuses such as those for computers, and further, signboards and indicating boards.
However, these resins are linear polymers and therefore, do not always have sufficient surface hardness, stiffness, heat resistance and chemical resistance. For purposes of improving these physical properties, silicone resins and acrylic resins are generally used for hard coating treatment, but in this case the solvents should be selected from very limited types of solvents from the standpoints of chemical resistance.
Further, according to the present level of coating technique, the thickness of the coating film is at most about 0.1 mm.
Therefore, the surface hardness and chemical-resistance of such resins can be fairly improved, but in view of the available maximum thickness of the coating film as mentioned above, it can not be expected to improve so far as heat resistance and stiffness. And when molded products of such resins are used as various members, thick molded products are required to prevent the members from deforming due to outer pressure or wind pressure.
As a transparent resin excellent in surface hardness and having an improved impact strength, diethylene glycol diallyl carbonate resins are widely known, but the volume shrinkage is as high as 14% and a long time is required until the polymerization is completed and moreover, the impact strength is still insufficient.
As mentioned above, there have not yet been found resins which can be satisfactorily used as a transparent material such as glazing materials.
In order to solve the above-mentioned problems in prior art, there are proposed various laminated resins as shown below.
(1) A laminated resin composed of a polymer or copolymer of monomer components containing a polymerizable monomer of (meth)acrylic acid esters as a substrate and a polymerizable monomer or prepolymer of (meth) acrylic acid ester capable of giving a more flexibility applied to the surface of the substrate or poured in between two sheets of the substrates to laminate the two substrates (Japanese Patent Application Laid-open No. Sho 53-2576); PA0 (2) A laminated resin composed of a polyurethane layer and an acrylic polymer layer, the two layers being independent from each other and simultaneously being penetrated into each other (Japanese Patent Application Laid-open No. Sho 63-252738); PA0 (3) A laminated resin composed of a polycarbonate resin molded product and a cured film of a ladder type silicone type oligomer formed on the surface of the polycarbonate resin molded product with an intervening (meth)acrylic acid ester copolymer (Japanese Patent Application Laid-open No. Hei 3-287634); PA0 (4) As a laminated resin intending to improve weatherability which is further demanded for resins used as a transparent material, a laminated resin produced by laminating a thermoplastic resin of high weatherability with a substrate of acrylic resin (Japanese Patent Application Laid-open No. Hei 3-30945). PA0 (5) There are proposed laminated resins produced by laminating a polymethyl (meth)acrylate resin to a polycarbonate resin molded product excellent in impact resistance so as to impart heat resistance and weatherability (U.S. Pat. Nos. 3,810,815, U.S. Pat. No. 3,933,964), but so far an improvement in surface hardness and stiffness can not be expected. In view of the foregoing, there have not yet been found novel materials for transparent resin molded products which possess satisfactory characteristics widely usable in industry, for example, as glazing materials.
These techniques have some drawbacks as to some physical properties. Technique (1) above can improve impact resistance while the surface hardness is not satisfactory. When the sheet of technique (2) above is used alone, the stiffness is not sufficiently assured and the surface hardness is not always sufficient. Technique (3) can improve the surface hardness while the stiffness is not satisfactory. Technique (4) gives a relatively excellent impact resistance and an improved weatherability while the stiffness and surface hardness are not satisfactory.